The effect of conflict history on cooperation within and between groups: Evidence from a laboratory experiment

•We study how conflict affects cooperation within and between groups in the lab.•We use a group Tullock contest to model conflict and induce strong group identity.•We manipulate group matching to disentangle in- and out-group effects of conflict.•Conflict increases cooperation within groups and decreases cooperation between groups.•We find no effect of the return on cooperation when groups share a history of conflict.